Cortisol and sex differentiation: the 11β-hydroxysteroid dehydrogenase as a key enzyme

SOMOZA, G.M.; FERNANDINO, J.I.; HATTORI, R.S.; STRÜSSMANN, C.A.

Qerétalo

Congreso; 2nd Meeting of the North American Society for Comparative Endocrinology; 2013

NASCE

In recent years, fish have been extensively studied because they present a variety of mechanisms of sex determination/differentiation. In the present work we review the sex determining mechanisms and the testicular differentiation process in Odontesthes bonariensis, commonly known as pejerrey, in relation to temperature-induced masculinization. We have recently shown that cortisol is involved in the gonadal masculinization process of pejerrey during early development. Larvae exposed to a male-producing temperature showed increased whole-body cortisol and developed as males. Moreover, they also have high 11-KT levels, suggesting a relation between cortisol and 11-oxygenated androgens during the masculinization process. 11β-hydroxysteroid dehydrogenase (11β-HSD) is one of enzymes shared by the glucocorticoid and androgen pathways. This enzyme converts cortisol to cortisone and also participates in the finals steps of the synthesis of the 11-oxigenated androgens. In pejerrey, during the critical period of sex determination, gene expression of the 11β-HSD gene hsd11b2, glucocorticoid receptors gr1, and androgen receptors (ar1 and ar2) were shown to be increased and expressed in the gonads during masculinization. These data suggest that the enzymatic machinery necessary for the local production of 11-oxygenated steroids and the inactivation of cortisol is active in the undifferentiated gonads during sex determination. Also, gonadal explants incubated in the presence of cortisol showed an increase in the synthesis of 11-KT. Based on these data, and also from data taken from the literature we here propose that the masculinization induced by thermal stress can be considered as a consequence of cortisol inactivation and the concomitant synthesis of 11-KT and discuss this as a possible mechanism of masculinization induced by different types of environmental stressors.